Safety device for elevators



July 19, 1932. sHlNN 1,867,991

SAFETY DEVICE FOR ELEVATORS Filed Oct. 13, 1928 2 Sheets-Sheet l mil 1 l flfiz 1 JAZ- July 19, 1932. $H|NN SAFETY DEVICE FOR ELEVATORS Filed Oct. 15, 1928 2 Sheets-Sheet 2 Patented July 19, 1932 UNITED STATES JOSEPH F. SHINN, OF HAGKENSAGK, NEW JERSEY SAFETY DEVICE FOR ELEVATORS Application filed October 13,

This invention relates to safety devices for elevators and, more particularly, to such devices as are operative to prevent the fall of an elevator car or lift if the supporting cable or other sustaining element, should break, or its normal tension should be slackened.

The principal provide a device of the character set forth which will function instantaneously to stop movement of the lift before the latter can gain any considerable momentum, and which is rendered operative directly by impairment of a sustaining cable.

Another object of the invention is to provide a safety device for elevators which is exceedingly simple in construction and operation, and which may be applied to any of the various forms of elevators commonly in use.

A further object is to provide a device of the character set forth which is not dependent in its operation upon springs or complicated systems of levers, but which on the other hand invokes the force of gravity in such a manner as to make the device instantaneously operable and to more securely sustain the weight of the elevator car, the greater I that weight may be. I

Other objects and advantages of the invention will in part be obvious, and in part more fully brought out as the description of the invention proceeds.

In the accompanying drawings I have illustrated a practical embodiment of my invention; but it is to be understood that the drawings are illustrative, merely, and are in no way to be considered as limiting the invention to the details of construction therein disclosed. Those skilled in the art will readily appreciate that the invention is suscepti ble of embodiment in other forms without sacrificing any of its salient features or departing, materially, from the scope of the invention as set forth in the appended claims.

In these drawings: I

object of the invention is to I 1928. Serial No. 312,266.

Fig. 1 is a side elevation of an elevator showing the safety device of my invention in its operative position caused by the breaking of a counterweight cable;

Fig. 2 is a rear view thereof, showing a similar safety device in its inoperative posi tion; v

Fig. 3 is a plan view; p v I Fig. t is a sectional view taken substantially on line fr-4: of Fig. 1; and

Fig. 5 is a view on an enlarged scale,.partly in elevation and partly in section, showing details of construction of the safety .de-

v1ce.

Referring now to the drawings,the refer- 5 ence numeral 1 indicates the elevator car or lift. This may be of any well known construction; it may be a passenger or freight car, and it need not be enclosed, but consist merely in a platform.

The car or lift is guided and confined in its movement by a frame-work 2' consisting of the upright guide-rails 3 and cross-frame members 4:; the guide-rails 3 being of angle shape in cross-section, as indicated in Fig. 4c. Each of the uide-rails 3 is provided with one or more bra e-engaging faces 5 for a purpose to be hereinafter more fully brought out.

Secured to the top of the car is a bracket 6 in which is pivotally mounted a lever 7, the lever being limited in its movement by a strap or guide 8. A pulley 9 is supported on the lever 7, and a hoisting cable 10 is trained about this pulley. The cable 10 is secured at one end to any suitable support at the upperend of the elevator shaft, and at the other end to the elevator hoist mechanism (not shown). To one end of the lever 7 is secured by means of an eye-bolt 11, or other suitable device, a cable 12 which at its other end is secured to a weighted member 13. v

The member 13 may be formed of cast iron or other material of great weight, or it may be made of lighter material having heavier metal inserts therein. The member 13 is free I to slide in a housing 14 which may be conveniently secured to the side of the elevator car or lift, or it may be mounted upon a separate side piece 15 secured to the bottom of the car. At its upper end, the member 13 is provided with shoulders 13a which contact with shoulders 1464 on the housing 14 when the cable 12 is taut, that is to say, when the cable is operating to lift the car.

At its lower end the weighted member 13 is bifurcated, as at 16, for the reception of a pair of brake-arms 17, which are pi votally mounted therein upon pivot pins 18.

Each of the brake-arms 17 is pivoted at its other end to a brake-shoe 19 provided with a braking-face 20. The brake-shoes 19 may be of any suitable construction and are provided with a recess 21 in which the end of the arm 17 enters.

In order to provide clearance for the braking-arms 17 with respect to the weighted member 13 and the brake-shoes 19, the arms are provided with cut-away shoulders as at 22 and 23, these shoulders being rounded Off to insure smoothness of operation and also to relieve the pivot pins of any undue stress.

From an inspection of Figure 5 it will be :lear that the member 13, which for the sake of convenience may be termed the brake operating member, and the brake-arms 17 form a toggle mechanism, the arrangement being such that when the weighted member 13 is moved upwardly, the brake-shoes are drawn out of contact with the braking-faces 5 of the rails 3, and when the member 13 descends, the brake-shoes are forced into engagement with the rails. In order to limit movement of the brake-shoes and to maintain them constantly in vertical position, I have provided lower stops 24 and upper stops 25, these being arranged to control the throw of the brake-shoes. It may here be stated that, normally, that is to say when the safety device is in its inoperative position, the brake-shoes are out of contact with the rails 3 and yet are located so near the rails that a small move ment of the member 13 will have the effect of immediately forcing the brake-shoes into engagement with said rails.

From the foregoing description it will. now be clear that so long as the hoisting cable 10 is maintained under tension, as is usual when it is operated to raise the elevator, that this tension in the cable will maintain the pivoted arm 7 in elevated position, and consequently the cable12 maintains the weighted member 13 in its upper position. It will be equally clear that should the cable 10 break or for some reason lose its normal tension, the arm 7 will be permitted to drop and the weighted member will, because of its great weight, immediately drop down, thus forcing the brake-shoes 19 into engagement with the rails. V

The foregolng arrangement has been described with reference to a mechanism operated directly by impairment of the hoisting cable 10. Such a mechanism is also and equally well adapted to be associated with the usual counterweight cables. In the present embodiment of my invention the elevator is provided with a pair of counterweight cables 26 which pass over pulleys 27 and 28 at the top of the elevator structure, and

which at their lower ends support a weighted member 13 similar to that heretofore described. These weighted members operate, respectively, pairs of brake-shoes'similar to those heretofore described. It is believed to be clear that so long as the counterweight cables remain intact and thus under tension, these weighted members 13 will be maintained in elevated position; but that as soon as the cable breaks or for any reason loses its tension, the weighted members 13 will, by the force of gravity, immediately drop, thus forcing the brake-shoes into engagement with the rails.

It will thus be seen that by my invention I have provided a safety device for elevators and similar structures which is exceedingly simple in construction and operation, and which becomes operative instantaneously if the elevator should begin to fall, due to the breaking of any of its suspending cables.'

The instantaneous action of my safety device is due to the fact that I do not employ springs or complicated systems of levers which must first be actuated before such devices generally become operative. It will also be clear that by providing braking devices of this type for each of the various sustaining cables generally employed in elevator structures, the effectiveness of the device is materially enhanced.

What I claim is:

1. In an elevator structure including a lift and a plurality of guide rails, a safety device comprising a housing secured to said lift, a pair of brake-shoes adapted to be moved into engagement with said rails, brake-operating means connected to said brake-shoes and slidably mounted in said housing, and stops engageable with the brake-shoes to maintain the same in operative position with respect to the rails.

2. In an elevator structure including a lift and a plurality of guide rails, a safety device including a pair of brake-shoes adapted to be moved into engagement with said rails, brake operating means connected to said brake-shoes, and stops engageable with the brake-shoes to maintain the same in operative position with respect to the rails.

3. In an elevator structure including a lift and a plurality of guide rails, a safety device including a pair of brake-shoes adapted to be moved laterally into engagement with the rails, a pair of longitudinally extending guide members on the lift, a weight slidable ice in said guide members, and actuating members operatively connecting the brake-shoes to said weight.

4. In an elevator including a lift and a plurality of guide rails, a safety device including a pair of brake-shoes adapted to be moved laterally into engagement with the rails, and stops engageable with the brakeshoes when they are in operative position with respect to the rails to support the same against longitudinal movement.

J OS. F. SHINN. 

